The range between 40°C (105°F) and 260°C (500°F) is divided in five temperature level groups per CelsiClock type. The temperature sensitive circular spots on the CelsiClock® change color permantently from white to black when their individual specified temperature rating is exceeded for less than a second. Printed in °C. Available in booklets (folder) with 10 identical rated labels, or on reels each 1000 pieces. $19.50/ Folder of 10 Price on request for reels